Dual engine locomotive

Abstract

A diesel-electric locomotive has two separate engine systems, including a large engine system and a small engine system. The power output from the separate engine systems may be combined to power the locomotive's traction motors. When the locomotive requires low power output for propulsion, only the small engine system is used to power the traction motors. When the locomotive requires higher power output, only the large engine system is used to power the traction motors. When the locomotive requires maximum power output, the small and the large engine system may both be used and their power output combined to power the traction motors. Also, a unique control strategy maintains a smooth delivery of power to the traction motors in the event that one engine shuts down or starts as a result of a change in the commanded power output of the locomotive.

We claim: 
     
       1. A method of operating a locomotive comprising:
 providing a small engine system including a small engine having a maximum rated power output of 1,000 brake horsepower (bhp); 
 providing a large engine system including a large engine having a minimum rated power output of 3,000 bhp; 
 commanding low power output of the locomotive for propulsion; 
 delivering electrical power to the locomotive for propulsion from the small engine system while the large engine system is turned off; 
 commanding higher power output of the locomotive for propulsion; 
 delivering electrical power to the locomotive for propulsion from the large engine system while the small engine system is turned off; 
 commanding a highest power output of the locomotive for propulsion; and 
 delivering electrical power to the locomotive for propulsion simultaneously from the large engine system and the small engine system. 
 
     
     
       2. A method according to  claim 1  wherein:
 the small engine system further includes a first traction electrical generator; 
 the large engine system further includes a second traction electrical generator; 
 the small engine is a small diesel engine; and 
 the large engine is a large diesel engine. 
 
     
     
       3. A method according to  claim 2  wherein:
 the small diesel engine has a rated power output of between 400 and 1,000 brake horsepower (bhp); and 
 the large diesel engine has a rated power output of between 3,000 and 4,200 bhp. 
 
     
     
       4. A method according to  claim 3  wherein the components of the small engine system are mounted to a separate frame, which is in turn mounted to the locomotive deck. 
     
     
       5. A method according to  claim 3  wherein the large engine system is mounted near a middle of the locomotive and the small engine system is mounted near a rear end of the locomotive. 
     
     
       6. A method according to  claim 1  further comprising:
 temporarily increasing the power output of either the small engine system or the large engine system in response to either commanding the higher power output or the highest power output. 
 
     
     
       7. A method according to  claim 1  further comprising:
 when the commanded power output for locomotive propulsion is increased, temporarily increasing the power output of the large engine system or the small engine system until the other of the large engine system or the small engine system begins to output electrical power for propulsion. 
 
     
     
       8. A method according to  claim 7  wherein:
 the small engine system further includes a first traction electrical generator; 
 the large engine system further includes a second traction electrical generator; 
 the small engine is a small diesel engine; and 
 the large engine is a large diesel engine. 
 
     
     
       9. A method according to  claim 8  wherein:
 the small diesel engine has a rated power output of between 400 and 1,000 brake horsepower (bhp); and 
 the large diesel engine has a rated power output of between 3,000 and 4,200 bhp. 
 
     
     
       10. A method according to  claim 9  wherein the components of the small engine system are mounted to a separate frame, which is in turn mounted to the locomotive deck. 
     
     
       11. A method of operating a locomotive comprising:
 providing a first engine system, the first engine system including a low horsepower small diesel engine having a maximum rated power output of 1,000 brake horsepower (bhp) and a first traction electrical generator; 
 providing a second engine system, the second engine system including a high horsepower large diesel engine having a minimum rated power output of 3,000 bhp and a second traction electrical generator; 
 commanding a first power output of the locomotive for propulsion; 
 delivering electrical power to the locomotive for propulsion from the first engine system while the second engine system is turned off in order to fulfill the command for the first power output; 
 commanding a second power output of the locomotive for propulsion which is more than the first power output; and 
 delivering electrical power to the locomotive for propulsion from the second engine system while the first engine system is turned off in order to fulfill the command for the second power output. 
 
     
     
       12. A method according to  claim 11  further including:
 commanding a third power output of the locomotive for propulsion which is more than the second power output; and 
 delivering electrical power to the locomotive for propulsion simultaneously from the first engine system and the second engine system in order to fulfill the command for the third power output. 
 
     
     
       13. A locomotive comprising:
 a first engine system including a first engine with a rated power output of between 400 and 1,000 bhp and a first traction electrical generator; 
 a second engine system including a second engine with a rated power output of between 3000 and 4,200 bhp and a second traction electrical generator; 
 a plurality of traction motors electrically connected to the first traction electrical generator and the second traction electrical generator; and 
 a control system for controlling operation of the first engine and the second engine to drive the locomotive. 
 
     
     
       14. The locomotive of  claim 13  wherein the first engine and the second engine are both internal combustion diesel engines. 
     
     
       15. The locomotive of  claim 13  wherein the control system is configured to operate the first engine and the second engine in a sequential manner until a maximum amount of power is required. 
     
     
       16. The locomotive of  claim 13  wherein the components of the first engine system are mounted to a separate frame, which is in turn mounted to the locomotive deck. 
     
     
       17. The locomotive of  claim 13  wherein the second engine system is mounted near a middle of the locomotive and the first engine system is mounted near a rear end of the locomotive.